Model output discussion 11/12/21

[Met4Cast]

A few comments re: seasonal models posted here a short while ago. It's entirely possible they are still factoring in a more central based La Nina during the initialisation, hence the more typical La Nina prediction of a +NAO/+AO during the second half of winter. 

What we're actually seeing is more of an east based La Nina developing, this combined with the -EPO/-PDO tends to favour a slower, more blocked jet stream during the later part of winter, so it's not necessarily all doom & gloom. 

Having said that, the MJO looks likely to become less influential during January, before that though we're looking at 14-20 days of blocking potential from the 22nd onwards.

Huge shift northwards on the latest EPS..

 

[geordiekev]

11 minutes ago, Hammer50 said:

Any winter historians out there ,I am wondering if we have had anything like this before prior to Xmas and what the outcome was.Just wondering.

You only have to go back to 2010 and the High Pressure in the Atlantic was modelled way before the event by the GFS I believe, though happy to be corrected. Ofcourse there was also the low pressure cells to keep the highs propped up

Edited December 14, 2021 by geordiekev

[E17boy]

Evening peeps

hope you all are well. I must say my brain is embedded in 1 word now High Pressure loll that’s been the main focus in the past several days and no doubt will continue being the main topic in the coming days. From my prospective I don’t think anything is resolved yet and there is more ups and downs to come yet till the position of this high gets sorted. 
 

We could be on the cusp of something special or this could all collapse in front of our eyes and we will be looking for the next cold chase. All the pieces of the jigsaw have to fall in place and fingers crossed this time they will. I have said many of times that I often monitor Europe temperatures to see what cold is piling up. There is good news temperatures are set to tumble for example Moscow was at minus 2 this week and by Thursday next week it’s predicted to go down to minus seventeen what a drop. So that’s one good news in the puzzle if we can manage to get our easterlies. 
 

But WINTER living here in NE London I have the following dream

.. High Pressure heads north

.. Bitter E or NE winds develop bringing significant windchill. 

.. It starts off dry then snow showers start pushing in from the North Sea.  
 

.. Snow showers become heavy as time goes on and prolonged many parts having significant accumulations.  
 

.. Day time temperatures are suppressed some places staying well below freezing all day even in Central London.  
 

.. A front comes in from the east or southeast and we get many hours of heavy falling snow. By which time many places record over a foot of lying snow.

…. Met office finally on board and issue red warnings for heavy snow widely

 

I suddenly wake up to reality and we are still waiting for winter. High pressure where will you go. Fingers crossed  

THE SEARCH FOR OUR WINTER WONDERLAND GOES ON

Have a great evening all

regards

 

[Daniel*]

On 14/12/2021 at 19:20, MATTWOLVES said:

Scatter means large spread of uncertainty Georgina...but keep an eye on the increasing amount of colder runs amongst the ensembles...the more runs that go colder the more of an  increased chance of that said outcome.

In ECM ens for Boxing Day you have coldest with a max of -1C in London and highest 13C! I can’t see it being anywhere near 13C myself.

[Kasim Awan]

39 minutes ago, Hammer50 said:

Any winter historians out there ,I am wondering if we have had anything like this before prior to Xmas and what the outcome was.Just wondering.

1962 had a fairly similar spell of retrogression similar to the colder end of the spectrum within the current potential.

Edited December 14, 2021 by Kasim Awan

[mountsbaysnow]

1 minute ago, Kasim Awan said:

1962

 

[Mike Poole]

7 minutes ago, Kasim Awan said:

1962

D’oh.  You made me look:

Boxing day 1962 and GEM T192 chart.

Some similarities there, you have to admit!  I think the biggest similarity is the Aleutian ridge and the Greenland ridge simultaneously.

Edited December 14, 2021 by Mike Poole

[Kasim Awan]

Just now, Mike Poole said:

D’oh.  You made me look:

Boxing day 1962 and GEM T192 chart.

Some similarities there, you have to admit!

The main difference is unavoidable, a climate change related expansion of the hadley cell, resulting in less favourable troughing into southern Europe.

[Staffmoorlands]

9 minutes ago, Daniel* said:

In ECM ens for Boxing Day you have coldest with a max of -1C in London and highest 13C! I can’t see it being anywhere near 13C myself.

BBC app showing 6c. I would expect it to be nearer freezing

[damianslaw]

Not passing much comment on the models at present, as I feel its one of those occasions where we just have to let them ride things out - we have high pressure about to descend on us, and it looks like it may hang around for quite some time.. shifting north possibly to enable something colder from the east possibly. It is rare to see high pressure stick direct over the UK at this time of year for more than a few days, but this one could have quite some staying power, which is interesting in itself. Temperatures should trend down, how low will depend on cloud amounts. 

Christmas Day is still 240 hrs away, and it won't be until Sunday at the earliest we can begin to say with some confidence likely development.

Interesting to see some of the models trending to something more unsettled over christmas with the atlantic moving in, but it looks half-hearted and I can't see any energy in the atlantic for quite some time.. a split jet could easily form, but uncertainty where most energy will be transferred northern or southern arm.. some longer range models including EC46 says southerly arm.

We are certainly in a very different place at this point in the year than most other years.. 2009 and 2010 we could say with confidence of a cold outlook, last 10 years a unsettled wet one, this year a settled one but questions on how cold.. 

 

 

[Kasim Awan]

1 minute ago, Staffmoorlands said:

BBC app showing 6c. I would expect it to be nearer freezing

It could be fairly tame if we tap into a weak easterly but fail to bring in any cold uppers. Moderation off north sea with 4c uppers & weak inversion -> 3-8C for England.

[Ali1977]

11 minutes ago, Staffmoorlands said:

BBC app showing 6c. I would expect it to be nearer freezing

The BBC App hasn’t updated since the 12z, I believe it uses the GFS forecasts. Expect a degree or 2 drop when it does update.

 

London on the ECM, Ice days at day 9/10

Edited December 14, 2021 by Ali1977

[Kasim Awan]

Arpege looks ok at 114h.

[feb1991blizzard]

7 minutes ago, Ali1977 said:

The BBC App hasn’t updated since the 12z, I believe it uses the GFS forecasts. Expect a degree or 2 drop when it does update.

 

London on the ECM, I’ve days at day 9/10

No - ukv (i think or uk4) for 36 hours (graphics - dont know about hourly), then ECM op until day 10 (graphics and hourly) then EPS for the rest.

[Updated_Weather]

On 14/12/2021 at 21:15, Ali1977 said:

The BBC App hasn’t updated since the 12z, I believe it uses the GFS forecasts. Expect a degree or 2 drop when it does update.

 

London on the ECM, I’ve days at day 9/10

Pretty sure they don’t use GFS at all. Think it’s a blend of UKV and ECM?

[Mapantz]

The app doesn't use the UKV. It's the Euro4 and ECM.

But an end to that discussion.. 

[TSNWK]

On 14/12/2021 at 21:15, Ali1977 said:

The BBC App hasn’t updated since the 12z, I believe it uses the GFS forecasts. Expect a degree or 2 drop when it does update.

 

London on the ECM, Ice days at day 9/10

And that is for a local warm spot of Heathrow..

[Allseasons-Si]

Evening all

i would just like to reiterate the fluid situation that we have on our hands/plate here.the models or NWP's (numerical weather pattern's) as in another way of putting it tend not to model heights very well say past 7 days away because of shortwaves developing in the mix once we count them down and how troughs negotiate with the block from the west,getting the right angle of attack against the block with a split flow of energy will determine where we might be heading,the more split flow of energy to the NW would sink the high and then the Atlantic will over rule the block and the more split flow of energy to the SE will undercut the block with a neg tilted low with the axis point from NW-SE,also in tandem we need the high far enough NW/N or NE to get the energy around the eastern periphery of the high to back the cold west and south towards the UK

lets have a look at some anomalies etc...

the NOAA/CPC 6-10 and 8-14 day 500mb forecast shows the high pressure centre just NW of Scotland/SE Iceland where as yesterdays showed it over N Ireland so todays has nudged it a bit further north with a possible neg tilted trough towards the Azores/Iberia 

also the gefs and ecm mean height anomalies for day ten show positive heights extending towards Greenland with negative heights underneath

here is an animation of the gefs mean 500mb height anomaly from 120 -384 hrs and this shows the positive heights transferring NW towards Greenland

gefs average 850 temps from Xmas day to new years eve,...def an easterly source there

and lastly the MJO from gefs and ECM ext'd,to me i think that these are more amplified than last evening's where the ECM was going towards/touching the COD(circle of death)

well that's me done for a little bit,...i need to rest me old little fingers ha ha

18z rolling out...

C U soon

 

 

 

Edited December 14, 2021 by Allseasons-si

[Don]

24 minutes ago, Kasim Awan said:

The main difference is unavoidable, a climate change related expansion of the hadley cell, resulting in less favourable troughing into southern Europe.

Yes and I imagine that will become more and more of an issue as the years tick by?!

[Kasim Awan]

1 minute ago, Don said:

Yes and I imagine that will become more and more of an issue as the years tick by?!

Hard to say. Atmosphere is too complex. One thing for sure is that it's a noticeable change.

[feb1991blizzard]

6 minutes ago, Allseasons-si said:

Evening all

i would just like to reiterate the fluid situation that we have on our hands/plate here.the models or NWP's (numerical weather pattern's) as in another way of putting it tend not to model heights very well say past 7 days away because of shortwaves developing in the mix once we count them down and how troughs negotiate with the block from the west,getting the right angle of attack against the block with a split flow of energy will determine where we might be heading,the more split flow of energy to the NW would sink the high and then the Atlantic will over rule the block and the more split flow of energy to the SE will undercut the block with a neg tilted low with the axis point from NW-SE,also in tandem we need the high far enough NW/N or NE to get the energy around the eastern periphery of the high to back the cold west and south towards the UK

lets have a look at some anomalies etc...

the NOAA/CPC 6-10 and 8-14 day 500mb forecast shows the high pressure centre just NW of Scotland/SE Iceland where as yesterdays showed it over N Ireland so todays has nudged it a bit further north with a possible neg tilted trough towards the Azores/Iberia 

also the gefs and ecm mean height anomalies for day ten show positive heights extending towards Greenland with negative heights underneath

here is an animation of the gefs mean 500mb height anomaly from 120 -384 hrs and this shows the positive heights transferring NW into Greenland

gefs average 850 temps from Xmas day to new years eve,...def an easterly source there

and lastly the MJO from gefs and ECM ext'd,to me i think that these are more amplified than last evening's where the ECM was going towards/touching the COD(circle of death)

well that's me done for a little bit,...i need to rest me old little fingers ha ha

18z rolling out...

C U soon

 

 

 

Here's the latest.

 

Look even better to me.

Edited December 14, 2021 by feb1991blizzard

[Daniel*]

On 14/12/2021 at 21:15, Ali1977 said:

The BBC App hasn’t updated since the 12z, I believe it uses the GFS forecasts. Expect a degree or 2 drop when it does update.

 

London on the ECM, Ice days at day 9/10

Wonder where you got that from  but nope that’s day 8 and 9… day 10 not displayed.

NAO continues to tumble with newer forecasts…

 

Yesterday’s EC46 kept -NAO through first half of January…

[Don]

3 minutes ago, feb1991blizzard said:

Here's the latest.

 

Look even better to me.

Yep, seen worse I think!  Very interesting but feet must be kept on ground for now!

[Allseasons-Si]

On 14/12/2021 at 21:40, feb1991blizzard said:

Here's the latest.

Ooops,...sorry about that,...my dry eye syndrome was getting the better of my eyesight that the date looks blury,...still...they look similar with perhaps more neg heights underneath on the ext'd

Edited December 14, 2021 by Allseasons-si
added info

[Ali1977]

6 minutes ago, feb1991blizzard said:

Here's the latest.

 

Look even better to me.

Yep, centre has moved a few hundred miles (maybe a hundred ) north from just below Iceland to just above